Bucket process for novelty regenerated cellulose yarn



Jan. 20, 1959 T. E. MITCHELL 9,

BUCKET PROCESS FOR NOVELTY REGENERATED CELLULOSE YARN Filed Oct. 28,1954 I INVENTOR THOMAS EDGAR MITCHELL BY MW ATTORNEY United States v.

BUCKET PROCESS FOR NOVELTY REGEN- ERATED CELLULOSE YARN Thomas EdgarMitchell, Chattanooga, Tenn, assignor to E. I. du Pont de Nernours andCompany, Wilmington, Del., a corporation of Delaware Application October28, 1954, Serial No. 465,313 3 Claims. (Cl. 57-157) This inventionrelates to the preparation of a novelty regenerated cellulose yarnparticularly suited for the production of textured fabrics. Morespecifically, it relates to the production from viscose of crinkled,nubby, continuous filanient,'regenerated cellulose yarn by the bucketprocess.

The importance of a novelty continuous filament yarn for preparingtextured or rough-surfaced fabrics is discussed in a copendingapplication to Lohr and Lulay, filedOctober 24, 1954, as Serial No.465,266. Briefly, the use of continuous-filament novelty yarns obviatesthe difficulties formerly faced by weavers and fabric-makers when theyused novelty-twisted two and three component yarns. The wool-like,resilient, sharp nubs, characteristic of loop yarns, slub yarns, knopyarns and boucles, tended to hang and catch in the fine apertures of thelooms and sewing machines. Crinkled, nubby, continuous filament yarnprovides wool-like, fluffy, resilient nubs along the length of yarn; butbeing a continuous filament, single-component yarn, the nubs do not tendto hang or catch in apertures during fabric preparation. Furthermore,the variationin denier of the crinkled, nubby yarn is sinusoidal ratherthan sharp. This characteristic also tends to ease the weaving problemand, surprisingly, without sacrificing any of the novelty texturedeffect.

To prepare crinkled, continuous filament, regenerated cellulose yarnhaving wool-like resilient nubs along its length, viscose (an alkalinesolution of cellulose xanthate) may be pulsated through spinneretorificesinto an acid-sulfate coagulating and regenerating bath. Thenubby filaments obtained are then fed over feed wheels, Whereregeneration into cellulose is substantially completed. From the feedwheels, the filament bundles, which make up the yarn, are led through atraversing funnel guide into a rotating bucket. The guide traverses upand down the depth of the bucket to throw the yarn by centrifugal forceagainst the inner wall of the bucket and thus to form the cake. Byplacing the guide in a position eccentric to the axis of the rotatingbucket, the yarn undergoes rapid fluctuations in the rate at which it isthrown against the inner wall of the bucket. this varying rate,alternating during each half thread revolution, that provides crinkl'mgand changes the compact nubs into Wool-like, resilient, flutfy nubs.Surprisingly, the crinkle effect tends to concentrate in the heavydenier portions (nubs) of the yarn. In general,.for optimum crinkling,the funnel guide should be placed about inch to /1 inch away from thecentral position over the bucket.

At this point, it is well to mention that between the point at which theyarn leaves the feed wheel and the point at which the yarn enters thefunnel guide, a ballooning effect is observed. In reality, theballooning is intermittent, varying with the rapid motion of thetraverse. The pattern and frequency of ballooning also change as thecake builds up.

It is.

2,869,319 Patented Jan. 2o, 1959 After a cake of predetermined size isformed within the bucket, it is doffed (withdrawn from the bucket) andthen Washed, desulfured, bleached and dried. The dried cake is thenunwound onto cones for shipment to fabric-v makers. Coning involveswithdrawing the yarn from the cake, usually upwardly, passing it throughguides, over an emulsion roll and then to a reciprocating thread guidewhich leads the yarn onto a spool where the cone is formed, The tensionbetween cake and cone is carefully regulated and kept very low topreserve the crinkle, in the yarn. The emulsion roll serves to apply alubricating compound to the yarn.

If the crinkled, nubby, continuous filament yarn is pre-, pared asindicated above, certain ditficnlties of a practical nature areencountered. The most serious of these, from the standpoint ofcommercial operation is that the cake formed in the bucket tends to becharacterized by tangles and snarls which make unwinding troublesomeand, in some cases, the tangles and snarls are so bad that it isvirtually impossible to. unwind the cake. Furthermore, even if the cakeis untangled and then unwound, it is observed that the crinkle along thelength of the yarn is not uniform which is a disadvantage.

The object of this invention is to provide an improved process for theproduction of crinkled, nubby, continuous filament, regeneratedcellulose yarn. A further object. is to produce crinkled, nubby,continuous filament, regenerated cellulose yarn cakes 'that'can beunwound onto cones without trouble. A still further object is to providea process of producing crinkled, nubby, con,- tinuous filament,regenerated cellulose yarn, wherein the crinkle is uniform throughoutthe length of the yarn. Other objects will appear hereinafter.

The objects of this invention are accomplished by a process whereinviscose is extruded through spinneret orifices into an acid-sulfatecoagulating and regenerating bath to form filaments having nubs alongtheir length; the resulting filaments passed over guide means such asfeed wheels, through a traversing funnel guide into a rotating bucket,wherein a cake of yarn is formed, said funnel guide located eccentric tothe axis of the bucket and wherein ballooning of the yarn between thefeed wheel and the funnel is maintained in the same condition throughoutthe formation of the cake.

The figure is a view in perspective of one form of apparatus useful inthe process of this invention.

informing regular continuous filament, regenerated cellulose yarn, aviscose filament-forming solution is led through the orifices of aspinneret into an acid-sulfate coagulating and regenerating bath. Toform nubby or variable denier yarn a pulsating motion may be imparted tothe viscose filament-forming solution prior to its p assage through thespinneret or the filaments after formation may be drawn at abruptlychanging linear speeds It is preferred to impart a pulsating motion tothe filament-forming solution prior to passage of the solution throughthe spinneret. This can be done by using a pulsating device between themetering pump and the spinneretto interrupt the flow either periodicallyor in randonrfashion, or by introducing a pulsating flow of filamert-forming solution into a line leading from the pump to the spinneret.Some specific devices for producing this nubby yarn include a variabledrive on a spinning pump, plunger pumps with plungers of unequaldiameters, gear-type pumps with uneven teeth or with some teeth removedfrom the gears, 21 main pump with auxiliary pumps to supply extraspinning solution at intervals, and pumps which do not supply spinningsolution but merely function to alter the pressure in the line leadingfrom the spinning pump to the spinneret.

The nubby, continuous filament, regenerated cellulose 3 yarn is then ledinto a rotating bucket through a funnel guide, located eccentric to theaxis of the bucket. However, for the improved process of this inventionthe ballooning, occurring betweenthe feed wheel and the funnel guide,must be controlled. This may be accomplished by the. device shown in thefigure.

In the figure, the yarn 11 is shown as it leaves the bath tank. Itpasses over the feed wheel 12 and snubber roller 13. After a second passover feed wheel 12 the yarn is led over a guide pin 14 which is mountedon strip 15. The strip is connected to the traversing mechanism, notshown, through the traversing rod 16. From guide pin 14 the yarn is leddownwardly through the funnel guide 17 into the rotating bucket 18. Thefunnel guide 17 is also connected to the traversing rod 16. The guide 17is placed eccentric to the axis 20 of the rotating bucket 18. Whentraversed up and down within the bucket, the guide serves to lay downthe cake 22 of crinkled, nubby, continuous filament, regeneratedcellulose. By having the guide pin 14 and the funnel guide 17, bothconnected to traverse rod 16, the distance between the guide pin 14 andmouth of the funnel guide 17 can be kept constant throughout thetraverse stroke. This would maintain a constant ballooning conditionthroughout the spin cycle if not for the effect on ballooning of thebuild-up of the cake within the bucket. To compensate for the elfect ofcake build-up, it is necessary to bring guide pin 14 slowly toward thefunnel guide 17 during the spin cycle. This may be accomplished bytelescoping the two sections of the traverse rod, 16a and 16b, so thatsection 16a, by means of a pawl arrangement, not shown, slips slowlydown within section 16b.. Alternately, the strip 15 instead of beingconnected to traverse rod 16, can be connected directly to the traversemechanism through a pawl arrangement. The funnel guide-17 would still beattached to the traverse rod 16. The pawl arrangement would serve tolower the guide during the spin cycle. In either case, the ballooningcondition would be maintained constant throughout the spin cycle.

The resulting cake is then dotted, washed, desulfured, bleached anddried in the conventional manner. There are no tangles and snarls in theresulting cake to interfere with winding. The cones are then prepared byunwinding the cakes; the only precaution is to maintain a low tension topreserve as much of the crinkle in the yarn as possible. As cones, theyarn is shipped to fabricmakers.

This process is useful for preparing crinkled, nubby, continuousfilament, regenerated cellulose yarn in deniers ranging from 200 denierto 4000 denier and higher. The nub spacing for optimum textured effectswill vary with denier. .200 denier yarn should have a spacing of about0.5 inch; 2000 denier yarn, a spacing of about 1.5 inches.Maximum-to-minirnum denier ratios will also vary with denier, in no casebeing less than 2:1. Contrast ratios as high as 8:1 is most desirablefor 2000 denier yarn.

In extruding the filaments into the acid-sulfate coagu- One of theimportant contributions of the present invention is that it makes anotherwise impractical operation commercially feasible. By maintaining aconstant balloon between the feed wheel and the funnel guide during theformation of the cake, an untangled cake is prepared. The theory of thissolution, which should not be considered limitative of this invention,lies in making the yarn behave in the same way from top to bottom of thetraverse stroke and throughout the spinning cycle. Thus, intermittentflashing into a balloon with accompanying pulling back of yarn alreadylaid down in the bucket is prevented. Pulling back yarn and feedingexcessive yarn alternately during the cycle probably contribute to thetangles and snarls in the cake.

The crinkled, nubby, continuous filament, regenerated cellulose yarnmade by the process of this invention is useful for preparing texturedfabrics of all varieties. Upholstery fabrics, drapery materials anddress goods are some of the important end uses.

Having fully disclosed the invention, Iclaim:

1. In the viscose process for producing a cake of crinkled, nubby,continuous filament, regenerated cellulose yarn, wherein afreshly-formed nubby yarn is led over guide means through a traversingfunnel guide into a rotating bucket, to form a cake therein, said funnelguide being located eccentric to the axis of said rotating bucket, theimprovement which comprises maintaining the ballooning condition betweensaid guide means and said funnel guide constant throughout the formationof the cake. v

2. In the viscose process for producing a cake of crinkled, nubby,continuous filament, regenerated cellulose yarn, wherein afreshly-formed nubby yarn is led over feed wheels, past a guide pin anddownwardly through a traversing funnel guide into a rotating bucket, toform a cake of yarn therein, said funnel guide located eccentric to theaxis of said rotating bucket, the improvement which comprises traversingsaid guide pin and said funnel guide at the same rate and loweringsaidguide pin toward said funnel guide to maintain the ballooningcondition between said guide pin and said funnel guide constantthroughout formation of the cake.

3. In the viscose process for producing a cake of crinkled, nubby,continuous filament, regenerated cellulose yarn, wherein freshly-formednubby yarn is led over feed wheels, past a guide pin and downwardlylthrough a traversing funnel guide into a rotating bucket, to form a cakeof yarn therein, said funnel guide located eccentric to the axis ofsaid, rotating bucket, the improvement which comprises traversing saidguide pin and said funnel guide at the same rate and over the samedistance and lowering said guide pin slowly toward said funnel guide tomaintain the ballooning condition between said guide pin and said funnelguide constant throughout formation of the cake.

References Cited in the file of this patent UNITED STATES PATENTS1,489,199 Dreaper Apr. 1, 1924 2,030,110 Keight Feb. 11, 1936 2,067,544Radestock Jan. 12, 1937 FOREIGN PATENTS 545,679 Germany Mar. 4, 1932644,806 Great Britain Oct. 18, 1950 804,336 France Aug. 3, 1936

1. IN THE VISCOSE PROCESS FOR PRODUCING A CAKE OF CRINKLED, NUBBY,CONTINUOUS FILAMENT, REGENERATED CELLULOSE YARN, WHEREIN AFRESHLY-FORMED NUBBY YARN IS LED OVER GUIDE MEANS THROUGH A TRAVERSINGFUNNEL GUIDE INTO A ROTATING BUCKET, TO FORM A CAKE THEREIN, SAID FUNNELGUIDE BEING LOCATED ECCENTRIC TO THE AXIS OF SAID ROTATING